Generally, catalyst bed reactors are mainly employed in petrochemical plants. The reaction modes that cause the reaction while liquid and gas reactants simultaneously flow into a catalyst bed include concurrent flow wherein both liquid and gas reactants flow downwards, and countercurrent flow wherein a liquid reactant flows downwards and a gas reactant flows upwards. As such, the reaction efficiency is determined by the contact efficiency of the liquid and gas reactants with the catalyst in the catalyst bed depending on the uniformity of flow of the reactants. Also, in the case where the gas and liquid reactants flow downwards at the same time in the reactor, a chimney tray is used so that the reactants are uniformly dispersed on the catalyst bed, and the number of chimneys is determined depending on the operating conditions of the reactor.
The chimney tray is typically disposed above the catalyst bed, so that a liquid/gas mixture is uniformly dispersed to the catalyst bed to maximize the use of the catalyst. While a predetermined level of the liquid is maintained outside the chimney tray, the liquid is fed into the chimney via holes and comes into contact with the gas being fed at a fast flow rate into the chimney, and is thus dispersed via the lower through-holes of the tray.
FIG. 1 illustrates a typical operation principle of a chimney tray for a catalyst bed reactor. The catalyst bed reactor needs a predetermined space 4 between a tray 1 and a catalyst bed 2. This space 4 enables the gas reactant to flow down at uniform pressure throughout the reactor, and the liquid reactant to be uniformly dispersed from the lower surface of the tray 1. A plurality of chimneys 3 is cylindrical shaped with a predetermined diameter and length and has outlets 3a, 3b having a predetermined diameter at the upper and lower portions thereof and penetrating therethrough. The tray 1 is provided with a plurality of through-holes 1a to edge of which the plurality of chimney 3 are perpendicularly bonded at lower ends thereof.
FIG. 2 shows a chimney tray for a reactor, which is used to more uniformly disperse a liquid reactant on a catalyst bed (Korean Patent No. 0421130), wherein a chimney 3 has a plurality of through-holes having a predetermined diameter, that is, a plurality of outlets which are formed to penetrate therethrough and face each other in a tangential direction with respect to the outer surface of the chimney 3 at the lower end thereof. Also, the outlet has an incline 1b at a predetermined angle along the edge of the lower end thereof. When the angle of the incline 1b increases, the area where the droplets of the liquid reactant spread out on the catalyst bed becomes larger, and the liquid reactant may flow in a radial direction to the axis of the chimney.
The conventional chimneys as shown in FIG. 1 are designed to enable the liquid reactant which flows via the outlets 3a, 3b of the chimneys 3 to collide with the opposite inner walls of the chimneys so that the liquid reactant breaks up into small liquid particles which are then sprayed via the through-holes 1a of the tray and thus uniformly dispersed on the catalyst bed 2. Under typical operating conditions of the catalyst bed reactor, the liquid reactant may flow at a predetermined rate inside the chimney 3, instead of breaking up into the liquid particles, and then may drop toward the lower central portions of the through-holes 1a of the tray 1. However, as the liquid reactant passes through the through-holes of the chimneys, it may intensively flow down to the central portion of the catalyst bed assigned to each chimney thus causing channeling of the liquid reactant and attrition of the catalyst, resulting in increased pressure of the reactor.
In the case of Korean Patent No. 0421130 of FIG. 2, the above problems are alleviated by radially dispersing the liquid reactant with respect to the axis of the chimney via the outlets in the tangential direction at the lower end of the chimney and by changing the angle of the incline 1b. However, the top of the chimney is exposed, and thus the liquid reactant is mixedly fed from the top of the chimney 3 which undesirably deteriorates dispersion performance. Furthermore, depending on the physical properties of the liquid reactant, the droplets may flow down to the lower surface of the tray 1 along the incline 1b, making it difficult to obtain desired dispersion performance.